North Columbia

A bit of new snow and an uptick in wind will feed into existing wind slab problems. Assess wind-drifted snow and lingering buried weak layers if you travel in avalanche terrain.  

TUESDAY NIGHT: Cloudy, light flurries with a trace of snow, light west wind with moderate gusts at ridgetop, alpine temperatures around -16 C.

WEDNESDAY: Mix of sun and cloud, light northwest wind with moderate gusts at ridgetop, alpine temperatures around -14 C.

THURSDAY: Sunny with a few clouds, light south wind with strong gusts in the afternoon, alpine temperatures around -11 C.

FRIDAY: Cloudy, 5-10 cm of snow, moderate southwest wind, alpine temperatures around -10 C. 

Since Monday, there have been several reports of small to very large (1.5-3) natural and human-triggered wind slab avalanches across a wide range of aspects above 2200 m. This MIN report from near Eagle Pass offers a helpful visual of this avalanche activity. Operators have also reported numerous small dry loose avalanches (size 1-1.5).

Observations of avalanches on the late January persistent weak layer continue to trickle in. This MIN report from the Gorge on Friday is a helpful example of the lower elevation slopes where the surface hoar has been preserved. Also on Friday, operators reported a large (size 2.5) natural avalanche on a southeast aspect in the alpine, releasing on facets. Over the past week the persistent slab problem has produced fewer avalanches than in the first week of February, but is still showing signs of instability and warrants assessment.

Light flurries have begun to accumulate over a variety of surfaces including surgary facets, feathery surface hoar, and wind-affected snow that formed as a result of last week's dry, cold weather. This trace of new snow and moderate northwest winds may feed into existing wind slab problems, especially in favored areas with up to 10 cm of accumulation. 

Winds have varied in strength and direction over the past week, loading cornices and forming wind slabs at upper elevations that may still be possible to trigger. Watch for these wind slabs in unusual places as complicated cross-loading and reverse-loading patterns are prevalent. Wind slabs may overlie weak, sugary, faceted snow, meaning that they could break wider than expected and will likely be slow to bond. 

60-100 cm of snow from February is settling over a layer of surface hoar buried in late January. Reactivity on this layer has primarily been observed at treeline and in "treeline-like" features, like cutblocks, that are below treeline. On steep south-facing terrain, this layer may consist of facets on a sun crust. 

The mid/lower snowpack is generally well settled and strong.

• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Approach lee and cross-loaded slopes with caution.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Extra caution is needed around cornices under the current conditions.